US-12623939-B2 - Biofilter with shaped underdrain assembly

Abstract

An improved biofilter design and related methods of utilizing shaped drain assemblies for directing fluid flow though a biofilter media to promote biological interaction. A shaped drain assembly can include a plurality of elongated drain structures having a permeable upper surface, a. lower surface and a drain interior defining a drain cross-section. When configured as a shaped underdrain assembly, each elongated drain structures can be in proximity to a biofilter tank floor such that the lower surface is in fluid communication with one or more flow channels below the floor and with the permeable upper surface supporting the biofilter media. The biofilter can include a shaped drain assembly positioned above the shaped underdrain assembly and located within or above the biofilter media. The shaped drain assemblies can control the flow and mixing of two or more flow species into the biofilter media.

Inventors

• Michael R. Ekholm
• Elsa Vulliez
• Clement Vitteau
• Fabrice Coura-Geot

Assignees

• AQSEPTENCE GROUP, INC.

Dates

Publication Date

20260512

Application Date

20210805

Claims (20)

1. 1 . A biofilter system, comprising: a tank defining a floor surface; a media bed; one or more flow channels defined below the floor surface; a shaped underdrain assembly including a plurality of elongated underdrain structures positioned on the tank floor, each elongated underdrain structure having a flume plate residing within the one or more flow channels, each elongated underdrain structure having a permeable upper surface, a lower surface in fluid communication with the flume plate and an underdrain interior so as to define an underdrain cross-section and wherein the permeable upper surface supports the media bed; and an upper shaped drain assembly including a plurality of elongated upper drain structures positioned above the shaped underdrain assembly, the upper drain structures having a permeable upper drain surface, an upper drain lower surface and an upper drain interior defining an upper drain cross-section, wherein the permeable upper drain surface comprises a slotted screen.
2. 2 . The biofilter system of claim 1 , wherein a flow interface is mounted within the underdrain interior, the flow interface allowing at least a first and second flow species to flow through the permeable upper surface.
3. 3 . The biofilter system of claim 2 , wherein the flow interface includes one or more of a flow orifice or a flow valve.
4. 4 . The biofilter system of claim 2 , wherein the at least first and second flow species include one or more of a process influent stream, a process effluent stream, an aeration inflow stream, an aeration outflow stream and/or a process additive inflow stream.
5. 5 . The biofilter system of claim 1 , wherein the permeable upper drain surface is positioned to face the permeable upper surface of each elongated underdrain structure.
6. 6 . The biofilter system of claim 1 , wherein the permeable upper drain surface is positioned to face away from the permeable upper surface of each elongated underdrain structure.
7. 7 . The biofilter system of claim 1 , wherein the upper shaped drain assembly is positioned within the media bed.
8. 8 . The biofilter system of claim 1 , wherein the upper shaped drain assembly is positioned above the media bed.
9. 9 . The biofilter system of claim 1 , wherein the permeable upper surface comprises a slotted screen.
10. 10 . The biofilter system of claim 1 , wherein the underdrain cross-section comprises a semi-circular section.
11. 11 . The biofilter system of claim 1 , wherein the underdrain cross-section comprises a rectangular or square cross-section.
12. 12 . The biofilter system of claim 1 , wherein the underdrain cross-section comprises a triangular cross-section.
13. 13 . The biofilter system of claim 1 , wherein the underdrain cross-section comprises a hexagonal cross-section.
14. 14 . The biofilter system of claim 1 , wherein the permeable upper surface comprises a surface coating selected to inhibit biological growth on the permeable upper surface.
15. 15 . The biofilter system of claim 1 , wherein the at least first and second flow species include a high flow species and a low flow species that are directed through the permeable upper surface in a shared direction.
16. 16 . The biofilter system of claim 1 , wherein a high flow species and a low flow species are directed through the permeable upper surface in opposed directions.
17. 17 . A method for promoting biological treatment in a biofilter, comprising: positioning a shaped underdrain assembly in a floor of a biofilter tank, the floor defining one or more flow channels and wherein the shaped underdrain assembly includes a plurality of elongated underdrain structures, each elongated underdrain structure having a flume plate residing within the one or more flow channels, each elongated underdrain structure further including a permeable upper surface, a lower surface and an underdrain interior so as to define an underdrain cross-section, and wherein each lower surface is in fluid communication with at least one of the flow channels through the flume plate; supporting a media bed on the permeable upper surface of each elongated underdrain structure; positioning an upper shaped drain assembly in the biofilter tank, the upper shaped drain assembly located above the shaped underdrain assembly, the upper shaped drain assembly including a plurality of elongated upper drain structures, each elongated upper drain structure including an upper drain permeable surface, an upper drain lower surface and an upper drain interior defining an upper drain cross-section, wherein the upper drain permeable surface comprises a slotted screen; and directing a fluid flow through the permeable upper surface to promote biological interaction in the media bed.
18. 18 . The method of claim 17 , wherein the step of directing the fluid flow through the permeable upper surface comprises: mixing a first flow species and a second flow species within the underdrain interior prior to directing a mixed flow stream through the permeable upper surface and into the media bed.
19. 19 . The method of claim 17 , wherein the upper drain permeable surface is positioned to face the permeable upper surface of each elongated underdrain structure.
20. 20 . The method of claim 17 , wherein the upper drain permeable surface is positioned to face away from the permeable upper surface of each elongated underdrain structure.

Description

PRIORITY CLAIM The present application is a National Phase Entry of PCT Application No. PCT/US2021/044839, filed on Aug. 5, 2021, which claims prior to U.S. Provisional Application Ser. No. 63/061,771 filed Aug. 5, 2020 and entitled, “BIOFILTER WITH SHAPED UNDERDRAIN ASSEMBLY”, all of which are hereby incorporated by reference in their entirety. FIELD OF THE INVENTION The present disclosure relates generally to biofilter systems for biological filtration of liquid streams. More specifically, the present disclosure is directed to an improved biofilter system utilizing shaped underdrain assemblies to improve flow distribution, simplify construction and reduce maintenance. BACKGROUND As opposed to liquid filtration systems that remove contaminant from liquid sources based upon size, conventional biofilter systems utilize a high surface area treatment media that promotes biological growth on the media surface to break down organic contaminants. Typically, biofilter systems utilize aeration to provide oxygen and nitrogen to promote the growth of bacteria on the surface of the treatment media. Depending upon the organic contamination within the liquid source, flow performance within the biofilter system is very important as even distribution and full utilization of treatment media is necessary to ensure a satisfactory residence time within the biofilter has been achieved. Biofilters generally utilize an underdrain support system at the bottom of a holding tank to support the treatment media. Conventional support systems typically comprise a network of pipes, nozzles and valves mounted within channels in the floor of the holding tank. These support systems can include structures for the distribution and collection of both air and liquid flow streams. Conventional support systems can be expensive and time consuming to install as well as being difficult to service and maintain. As such, it would be advantageous to improve upon current biofilter design through the use of an improved underdrain support system. SUMMARY In representative embodiments of the present disclosure, there is provided an improved biofilter design utilizing shaped drain assemblies to support a treatment media and to promote air and liquid flow through the treatment media. In representative embodiments of the present disclosure, there is provided an improved biofilter design utilizing shaped drain assemblies to support a treatment media and to promote air and liquid flow through the treatment media. In some embodiments, the shaped drain assemblies are arranged as underdrain assemblies arranged on or in proximity to a floor of a biofilter tank such that the underdrain assembly supports a biofilter media bed. In some embodiments, the shaped drain assembly can be arranged above the floor of the biotank filter and either within or above the biofilter media bed. In some embodiments, the shaped drain assemblies can comprise multiple drains assemblies, for example, a shaped underdrain assembly on the floor of the biotank filter and another shaped drain assembly positioned above the underdrain assembly and either within or above the biofilter media bed. Regardless of orientation in the biofilter tank, the shaped drain assembly can comprise a plurality of elongated drain structures having a permeable upper surface, a lower surface and a drain interior defining a drain cross-section. Each elongated drain structure can comprise one or more fluid connections including flow controls such as flow orifices and flow valves to control flow one or more fluid streams, liquid or gas, into the drain interior where the one or more fluid streams can be directed through the permeable upper surface and in some embodiments, induce mixing of multiple fluid streams within the drain interior. In some embodiments, each elongated drain structure includes a flow interface within the drain interior to control flow of two or more fluid species through the permeable upper surface. In one aspect, the present invention is directed to a biofilter system utilizing a shaped underdrain support system. An embodiment of the biofilter system can comprise a biofilter tank, a biofilter media and a shaped underdrain assembly. The biofilter tank can have a tank floor with one or more flow channels defined below a floor surface. The shaped underdrain assembly includes a plurality of elongated underdrain structures, wherein each elongated underdrain structure comprises a permeable upper surface, a lower surface and an underdrain interior defining an underdrain cross-section. Each elongated underdrain structure can be positioned across one or more of the flow channels such that the lower surface is in fluid communication with the one or more flow channels. The elongated underdrain structures can be fabricated such that the underdrain cross-section has desirable properties including, for example, fluid flow properties through the permeable upper surface and mechanical strength to support the blot